DATA: Randy Cohen takes on the age old debate: surfing porn at the library. (I've actually seen this myself at the SPL. Apparently I behaved ethically by Cohen's standards by keeping my "ew, a bum with a boner" disgust to myself and moving to another terminal. Yes it was distracting but no it wasn't a big deal.)

I was disturbed to see a man looking at pornography on a New York Public Library computer. When two children sat down near him, I decided to take action, but he instantly switched to an inoffensive video game. A security guard told me they were keeping an eye on a couple of people acting similarly and would catch them in the act eventually. Should I have alerted someone as soon as I became aware of this man's activities? -Anonymous, New York

A guard monitoring someone's reading? That's not my idea of how a library operates. Libraries should provide for the free exchange of ideas -- not just ideas you or I find palatable, not just ideas suitable for 5-year-olds. And librarians should not be forced to censor patrons' reading, let alone eject them for looking at disturbing images.

Happily, even if you and the overeager guard had reported this incident, nobody would have been rousted. Caroline Oyama, manager of public relations for the New York Public Library, explains that it ''does not ask adult patrons to leave, stop what they are doing or move to another computer if another patron doesn't like the Web site he or she is viewing. Instead, we make every attempt to move the user who is offended to another computer where he or she doesn't have to see what the other person is viewing.'' This is a prudent policy, consistent with the library's ethos and responsive to the sensitivities of patrons of all ages.